INCREASES IN LEAD AND pH LEVELS
FOLLOWING CEMENT MORTAR LINING IN LOW ALKALINITY AREAS
Report No DWI0291
To determine whether the increase in pH levels seen after cement mortar lining will increase lead concentrations at the consumers' tap.
When small diameter mains with low flows in low alkalinity water areas are lined with cement mortar, the pH of the conveyed water can be elevated above the EC directive MAV of 9.5 for a considerable time. This work investigates whether an increase in pH will lead to an increase in plumbosolvency.
Initial laboratory studies indicated that at pH levels above 10 the plumbosolvency would increase significantly.
Field trials confirmed that lead concentrations would be increased at high pH levels but if the pH levels were kept below 10.5 the lead concentrations should remain below the current EC directive MAC.
To reduce the risk of high lead concentrations after cement mortar lining the p8 levels should be kept below 10.5.
Further field trials may be required to determine whether these results are applicable to other water quality areas.
The EC directive MAC relating to lead concentrations is currently being revised. The conclusions of this report may require revision in the light of future changes to the MAC.
Laboratory studies of Humberside College of Higher Education were conducted to determine whether plumbosolvency was increased at high pH levels due to lime. A field trial was then carried out in Birmingham to check whether the laboratory results applied under normal cement mortar lining conditions.Copies of this report may be available as an Acrobat pdf download under the 'Pre 2000 Reports' heading on the DWI website.